The present invention deals with a system for treating an aneurysm. More specifically, the present invention is directed to a system for deployment of an aneurysm liner within the aneurysm.
An aneurysm is a localized stretching or distension of an artery due to a weakening of the vessel wall. For example, xe2x80x9cberryxe2x80x9d aneurysms, i.e., small spherical distensions, occur in the vessels of the brain. The distensionsxe2x80x94often referred to as the aneurysm sacxe2x80x94are related to defects in the muscular coating of the artery and are probably degenerative in origin. Rupture of aneurysms account for the majority of spontaneous hemorrhages. Approximately 25,000 intracranial aneurysms rupture every year in North America.
Several methods of treating aneurysms have been attempted, with varying degrees of success. At present, the treatment of aneurysms with drugs is substantially ineffective. Also, extra-vascular surgery, referred to as open craniotomy, for the purpose of preserving the parent artery is replete with disadvantages. A patient subject to open craniotomy for intercranial aneurysms typically must undergo general anesthesia, surgical removal of part of the skull, brain retraction, dissection around the neck of the sac, and placement of a clip on the parent artery to prevent bleeding or rebleeding.
Alternative treatments include endovascular occlusion where the interior of the aneurysm is entered with a guidewire or a microcatheter. An occlusion is formed within the sac with an intention to preserve the parent artery. A preferred means for forming a mass is through the introduction of an embolic agent within the sac. Examples of embolic agents include a detachable coil, which is detached from the end of a guidewire, and a liquid polymer which polymerizes rapidly on contact with blood to form a firm mass.
Endovascular occlusion is not without drawbacks. For example, there is a risk of overfilling the sac and consequent embolic agent migration into the parent vessel. overfilling of the sac also generates additional pressure in the aneurysm.
Another means for forming a mass in the aneurysm sac involves the placement of an expandable balloon or liner in the aneurysm. Detachable occlusion balloons have been used for a number of medical procedures. These balloons are carried at the end of a catheter and, once inflated can be detached from the catheter. Such a balloon may be positioned within an aneurysm, filled and then detached from the catheter. Deploying the balloon within the aneurysm can be rather difficult due to the high rates of blood flow through the aneurysm. Elastic balloons have exhibited problems with respect to performance and have not been used endovascularly in some time.
This aneurysm filling technique also has its problems. As the balloon is filled, the operator must be very careful not to overfill the balloon due to possible risk of rupturing the aneurysm. Accordingly, the balloon may be too small, potentially resulting in the release of the balloon from the aneurysm into the blood stream. Furthermore, the balloon often does not mold or shape to the odd-shaped contours of the aneurysm leaving room for blood to continue flowing through the aneurysm, or generating undesired pressure on the aneurysm wall.
Aneurysm liners are composed of a liner sac which is placed in the aneurysm and filled to occlude the aneurysm. A guidewire is inserted in the liner. The guidewire carries the liner through the vasculature to deploy the liner in the aneurysm.
The delivery and deployment of aneurysm liners pose similar problems to the occlusion balloons. In addition, current aneurysm liners require the use of specific guidewires in order to hold the liner in a low profile position so it can be advanced through the vasculature. The guidewire is required to be extended distally of the liner by a fixed amount when the liner is introduced into the aneurysm. This makes it difficult to place the liner in the aneurysm and requires a xe2x80x9cbumperxe2x80x9d on the wire to contact a marker band and extend the sac or liner. Further, the extension of the guidewire past the distal end of the sac can be problematic when placing the sac into an aneurysm as the extended tip can increase the risk of rupturing the aneurysm.
An improved aneurysm liner is used for treating an aneurysm in a parent vessel. The parent vessel defines a lumen. The aneurysm includes a neck and an inner wall defining a cavity in fluid communication with the lumen. The liner device is configured for deployment within the cavity. The device includes an extender inside an expandable aneurysm liner. The proximal extender end receives force from a distal end of a delivery catheter for maneuvering the device into a deployment position. The device is arranged such that, when deployed within the cavity, the liner expands to fill the cavity.
In treating an aneurysm, the liner device is directed to the aneurysm site by a guidewire that extends through the extender. Upon removal of the guidewire, the extender is released within the liner and the liner is allowed to relax. The liner is then expanded, by introducing embolic material therein, to fill the cavity.